Dr. William Massello III, the state medical examiner, said in his report that Cory Smoot died of "coronary artery thrombosis brought about by his pre-existing coronary artery disease." The formation of such blood clots can result in a heart attack.
Smooth, 34, had performed since 2002 under the name "Flattus Maximus" with the Virginia-based band known for its comically grotesque sci-fi/fantasy-based costumes, stage antics and vulgar lyrics.
He was found dead Nov. 3 on the GWAR tour bus in the North Dakota town of Pembina following a concert the night before in Minneapolis.
The band packed their equipment after finishing the Minneapolis show and left around 2 a.m., sleeping en route to upcoming shows in Edmonton and Calgary, Alberta.
Prior to crossing the U.S.-Canadian border, the driver pulled into Pembina to make sure the group's passports were in order. Everyone's passport was found except for Smoot's, so tour manager Eddy Oertell tried to wake him and discovered he was dead, according to reports.
Records show that investigators found on Smoot a $5 bill with a white powder residue, a prescription bottle holding eight Oxycodone-Acetaminophen pills, a lighter and two empty syringes.
GWAR lead singer Dave Brockie, also known as "Oderus Urungus," said the band is embarking on the European portion of its tour in January as a four-piece outfit.
"When Cory died, we all wanted to go home and take care of the family and our own grief," Brockie said on the band's website. "But the best way to do that is by playing all the shows we have planned."